>     It you use a bitbang software UART you can measure the start bit
> duration and use it as a reference for other bit's position. That way you
> can compensate for variations on the clock caused by temperature changes.
> The temperature changes are usually not too fast. With the hardware uart
you
> better use a resonator...

You can only use the start bit for bit duration timing if the next bit has
the opposite sense.  Only the start and stop bits have guaranteed polarity.
It is possible to watch the bits going by and eventually deduce the bit
timing, but not trivial.  If you have a rough idea of the baud rate so that
the start and stop bits can be identified, then it becomes easier.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body